1. Title of the Invention
The present invention relates generally to a microwave oven of the type including a duty cycle control to vary power level, and more particularly to a means for decreasing the magnetron power by way of a plurality of intermediate power levels during the thawing of different food products.
2. Description of the Prior Art
An often used method for thawing processed and prepared foods in a microwave oven involves setting a program timer for a desired span of time while keeping the magnetron power level relatively low. The thawing period and the power level may depend upon the quality of nature of the food, however, and thus deciding the time-power level conditions is known to be intricate.
In the meantime there has been developed a control system called a duty cycle control in which the power transformer and the magnetron are alternately switched between a full-on operation and a full-off operation. The ratio of "on" time compared to the total operation time is known as the duty cycle. The average magnetron power level is the actual power output of the microwave oven.
Various particular circuits have been proposed to effect duty cycle power control. These control systems range from a simple cam-functioned mechanical timer, to more advanced systems adopting electronic timing and switching elements.
Although the above-described methods and systems are in practical use, no appropriate power control systems have been made available that function in relation to the temperature of the food undergoing thawing.